JP6012526B2 - Alkali metal thermoelectric converter - Google Patents

Description

  The present invention relates to an alkali metal thermoelectric converter, and more particularly to an alkali metal thermoelectric converter using a solid electrolyte.

  An alkali metal thermoelectric converter (AMTEC) using β or β "alumina having conductivity of alkali metal ions such as sodium ions as a solid electrolyte is known (for example, Patent Document 1). And a vacuum-sealed container having a high-temperature portion that receives heat from the outside and becomes a high temperature (600 to 1000 ° C.) and a low-temperature portion that dissipates heat and becomes a low temperature (100 to 500 ° C.). A circulation path is defined so as to pass through the high temperature part and the low temperature part, and an alkali metal is enclosed in the circulation path. In the circulation path in the high temperature part, a solid electrolyte that is β or β ″ alumina is added to the circulation path. Is provided so as to be divided into a first chamber and a second chamber. The first chamber is provided with an anode, and the second chamber is provided with a cathode. A pump such as a wick pump or an electromagnetic pump is provided in the circulation path, and the liquid alkali metal in the circulation path in the low temperature part is transported to the first chamber by the pump.

  The liquid alkali metal transported to the first chamber becomes high temperature in the first chamber, and a part thereof becomes a gas. The gaseous alkali metal emits electrons on the surface of the solid electrolyte to become alkali metal ions, and enters the solid electrolyte. The emitted electrons flow to the anode. The alkali metal ions that have entered the solid electrolyte pass through the solid electrolyte and receive electrons from the cathode on the surface on the second chamber side to become gaseous alkali metal. Thus, when alkali metal ions pass through the solid electrolyte, electrons flow from the anode to the cathode via the external load, and a current is generated. The gaseous alkali metal existing in the second chamber flows to the low temperature portion, condenses, and is transported to the first chamber again by the pump. The alkali metal thermoelectric conversion device configured as described above can be said to be a concentration cell that utilizes the difference in alkali metal concentration between the first chamber side and second chamber side surfaces of the solid electrolyte.

  The power generation efficiency of the alkali metal thermoelectric converter depends on the amount of alkali metal ions passing through the solid electrolyte. Therefore, the power generation efficiency is increased by a method for increasing the surface area of the first chamber side and the second chamber side of the solid electrolyte and a method for increasing the concentration difference (vapor pressure difference) of the alkali metal in the first chamber and the second chamber. be able to.

Japanese Patent Laid-Open No. 3-178484

  In the alkali metal thermoelectric converter as described above, since the electromotive force in a single cell is 0.1 to 0.7 V, a plurality of cells are connected to each other so as to obtain a necessary potential (output voltage) according to the application. There is a need. However, if a plurality of cells are simply gathered together, there is a problem that the volume of the entire apparatus increases. In particular, the entire apparatus is enlarged because the means for transporting the liquid alkali metal such as an electromagnetic pump provided in each cell overlaps the entire apparatus. Further, there is a problem that the wiring structure for connecting each cell becomes complicated and the device configuration becomes complicated.

  This invention is made | formed in view of the above background, Comprising: It makes it a subject to comprise simply and compactly the alkali metal thermoelectric converter which contains several cells and has a high output voltage.

  The alkali metal thermoelectric converter (10) according to the present invention includes a high temperature side housing (32) that receives heat and a high temperature side, a low temperature side housing (54) that dissipates heat and a low temperature, and the high temperature side housing (32). The high temperature chamber (36) is divided into a first chamber (36A) and a second chamber (36B), a solid electrolyte (38) that allows passage of alkali metal ions, and the first chamber (36A). ), The cathode (48) provided in the second chamber (36B), the low temperature chamber (56) in the low temperature housing (54), and the first chamber (36A). Of the liquid stored in the low temperature chamber (56), the second passage (62) communicating with the low temperature chamber (56) and the second chamber (36B). A plurality of cells (30) having an alkali metal and the front The cell (30) is arranged around one rotation axis (X), the high temperature side housing (32) is arranged on one side along the rotation axis (X), and the low temperature side housing (54) is rotated. A series connection circuit (82, 84, 86, 88, 90, 92) disposed on the other side along the axis (X) and further electrically connecting the plurality of cells (30) in series; A drive device (70) for rotating all of (30) around the rotation axis (X), and the inside of the low temperature chamber (56) by centrifugal force generated by rotation about the rotation axis (X) The alkali metal is moved to the first chamber (36A) through the first passage (66).

  According to this configuration, since the plurality of cells (30) are electrically connected in series, a high output voltage can be obtained. In series connection, the alkali metal must circulate in an independent flow for each cell (30) to avoid electrical shorting between the cells (30) due to liquid alkali metal. On the other hand, since the transport for circulating the alkali metal is performed by the centrifugal force generated by rotating the cell (30) around the rotation axis (X) by the driving device (70), the cell (30 ) It is not necessary to provide a transportation means for transporting the alkali metal every time. Thereby, the alkali metal thermoelectric converter (10) which connected the some cell (30) in series can be comprised compactly avoiding duplication of a transport means.

  The alkali metal thermoelectric converter (10) according to the present invention preferably has a plate-like member (16) extending in a direction orthogonal to the rotation axis (X), and the cell (30) is the high temperature side housing. (32) and the low temperature side housing (54) are configured separately, and all of the high temperature side housing (32) is fixed to one side of the plate-like member (16), and the low temperature side housing (54) Are fixed to the other side of the plate-like member (16).

  According to this configuration, the high temperature of each cell (30) on one side of the plate-like member (16) forming a common support for the individually configured high temperature side housing (32) and low temperature side housing (54). Since the side housing (32) is collected and the low temperature side housing (54) of each cell (30) is collected on the other side, the structure is simplified and at the same time the plate-like member (16) is And the low temperature side are clearly partitioned, and the temperature management of the alkali metal thermoelectric converter (10) becomes easy.

  In the alkali metal thermoelectric converter (10) according to the present invention, preferably, the high temperature side housing (32) is made of a conductive material and also serves as the anode, and the plate member (16) is made of an electrically insulating material. Has been.

  According to this configuration, since the high temperature side housing (32) also serves as the anode, it is not necessary to separately configure the anode on the anode side of the solid electrolyte (38). As a result, the fins 46 can be provided on the anode side surface 42 of the solid electrolyte 38 without being restricted by configuring the anode. Since the plate member (16) is made of an electrically insulating material, the high temperature side housing (32) is electrically connected between the cells (30) even if the high temperature side housing (32) is made of a conductive material. A plurality of cells (30) can be electrically connected in series without being short-circuited by insulation.

  The alkali metal thermoelectric converter (10) according to the present invention preferably has a rotating shaft (12) disposed concentrically with the rotating axis (X) and having the plate-like member (16) attached thereto, One of the anode side and cathode side slip rings (76) is attached to the rotating shaft (12) in an electrically insulated state, and the other (78) is attached in an electrically conductive state. One terminal of the circuit is conductively connected to the one slip ring (76) in an electrically insulated state from the rotating shaft (12), and the other terminal of the series connection circuit is conductively connected to the rotating shaft (12). ing.

  According to this configuration, the rotating shaft (12) forms a part of the conductive path, and the conductive connection structure between the series connection circuit and the other slip ring (78) is simplified.

  In the alkali metal thermoelectric converter (10) according to the present invention, preferably, each of the high temperature side housings (32) is disposed at a rotationally symmetric position around the rotation axis (X), and the low temperature side housing ( 54) are also arranged at positions that are rotationally symmetric with respect to the rotation axis (X).

  According to this configuration, even if the high temperature side housing (32) and the low temperature side housing (54) rotate around the rotation axis (X) to obtain a centrifugal force, an imbalance in rotational balance due to eccentric load may occur. Absent.

  In the alkali metal thermoelectric converter (10) according to the present invention, preferably, a portion where the solid electrolyte (38) faces the first chamber (36A) side is uneven for expanding the surface area of the solid electrolyte (38). (46) is provided.

  According to this configuration, the contact area between the portion of the solid electrolyte (38) facing the first chamber (36A) and the alkali metal is increased, and the alkali metal ions that emit electrons and enter the solid electrolyte (38). The amount of increases. Accordingly, the amount of electrons separated on the anode side of the solid electrolyte (38) increases, and the power generation capacity increases.

  In the alkali metal thermoelectric converter (10) according to the present invention, preferably, the high temperature side housing (32) is arranged to be able to exchange heat with the exhaust gas of the internal combustion engine.

  According to this configuration, the alkali metal thermoelectric converter (10) operates by using waste heat.

  According to the alkali metal thermoelectric converter of the present invention, the alkali metal in each cell is transported by the centrifugal force generated by rotating the cell around the rotation axis by the driving device, so that the alkali metal is transported for each cell. There is no need to provide individual transportation means. Thereby, the alkali metal thermoelectric converter which connected the some cell in series can be comprised compactly avoiding duplication of a transport means.

The perspective view which shows one Embodiment of the alkali metal thermoelectric converter by this invention. Sectional drawing of the alkali metal thermoelectric converter along line II-II of FIG. 3 (illustration of the cell of # 2 and # 3 is abbreviate | omitted). FIG. 3 is a sectional view taken along line III-III in FIG. 2. Sectional drawing along line IV-IV of FIG. The schematic block diagram which shows the usage example of the alkali metal thermoelectric converter by this invention.

  Hereinafter, one embodiment of an alkali metal thermoelectric converter according to the present invention will be described with reference to FIGS.

  The alkali metal thermoelectric converter (AMTEC) 10 has a rotating shaft 12 made of a conductive material such as metal extending vertically (vertical direction). A disk member (plate-like member) 16 is fixed to an intermediate portion in the axial direction of the rotating shaft 12 by a flange portion 12A integrally formed with the rotating shaft 12 and a fixing ring 14 (see FIG. 2) engaged with the rotating shaft 12. Has been. The disk member 16 is made of an electrically insulating material having heat resistance such as ceramic, and extends in a direction (horizontal direction) perpendicular to the central axis of the rotary shaft 12, that is, the rotary axis X. It can be said that the rotating shaft 12 is disposed concentrically with the rotating axis X.

  The AMTEC 10 is disposed in a high temperature environment of 500 ° C. or more above the disk member 16, and is disposed in a low temperature environment of about 100 to 500 ° C. below the disk member 16.

  In the disk member 16, openings 18 as many as the number of cells 30 to be described later are formed penetratingly in the axial direction (vertical direction) at rotationally symmetric positions around the rotational axis X. In the present embodiment, since the number of cells 30 is 6, the openings 18 are arranged at equal intervals around the rotation axis X with a rotation angle of 60 degrees. The planar shape of the opening 18 is substantially fan-shaped as shown in FIG.

  A cell mounting substrate 20 made of a conductive material such as metal having a planar shape similar to the planar shape of the opening 18 (see FIG. 3) is attached to the upper surface of the disk member 16 so as to close the upper side of each opening 18. . A disc-shaped two-layered insulating plate 22 is attached to the upper surface of each cell mounting substrate 20. Each insulating plate 22 is made of an electrically insulating material having heat resistance such as ceramic, and is disposed at a rotationally symmetric position around the rotation axis X.

  On the insulating plate 22, the high temperature side housing 32 of each cell 30 is attached. Another disk member 26 is attached to the upper end portion of the rotary shaft 12 so as to be sandwiched by a nut 24 screwed to the upper end portion. The disk member 26 is made of an electrically insulating material having heat resistance such as ceramic, and is in contact with the upper end surface of the high temperature side housing 32 of each cell 30. Thereby, all the high temperature side housings 32 of each cell 30 are sandwiched from the axial direction by the electrically insulating disk members 16 and 26 so as to maintain individual electrical insulation without being electrically short-circuited with each other. Are fixed to the rotary shaft 12.

  Each of the high temperature side housings 32 exists individually for each cell 30, and is disposed on the insulating plate 22 of each cell mounting substrate 20, so that the high temperature side housings 32 are rotationally symmetrical with respect to each other about the rotation axis X. They are arranged at regular intervals around the rotation axis X with a rotation angle of 60 degrees.

  The high temperature side housing 32 is made of a conductive material such as a metal having high thermal conductivity and electrical conductivity, and has a cylindrical shape with a lower opening whose upper end is closed by an end wall 32A. In the cylindrical portion 32B of the high temperature side housing 32, a plurality of fins 34 projecting radially outward from the outer peripheral surface are integrally formed in order to increase the heat exchangeable surface area. In the present embodiment, the fins 34 are provided over the entire circumference of the cylindrical portion 32B to form an annular shape.

  As shown in FIG. 2, the high temperature side housing 32 cooperates with the insulating plate 22 forming the bottom plate of the high temperature side housing 32 to define a high temperature chamber 36 having a sealed structure therein. The high greenhouse 36 is provided with a solid electrolyte 38 that allows passage of alkali metal ions. In the present embodiment, the solid electrolyte 38 is a β-alumina solid electrolyte or β "alumina solid electrolyte that allows sodium ions to pass at a high temperature, and the upper end is formed by the end wall 38A by a sintered material of β-alumina or β" alumina. It is sintered and formed into a cylindrical shape with a closed lower opening.

  The solid electrolyte 38 is disposed on the insulating plate 22 concentrically with the high temperature side housing 32 in the high temperature chamber 36, and the high temperature chamber 36 is partitioned into a first chamber 36A and a second chamber 36B with the insulating plate 22 as a bottom plate. The first chamber 36 </ b> A is outside the solid electrolyte 38, and the second chamber 36 </ b> B is inside the solid electrolyte 38. The outer surface (surface on the first chamber 36A side) of the solid electrolyte 38 forms an anode (cathode) side surface 42, and the inner surface (surface on the second chamber 36B side) of the solid electrolyte 38 forms a cathode (anode) side surface 44.

  A plurality of fins 46 projecting radially outward from the outer peripheral surface are integrally formed on the cylindrical portion 38B of the solid electrolyte 38 by sintering in order to increase the surface area of the outer peripheral surface of the solid electrolyte 38, that is, the anode side surface 42. ing. In the present embodiment, the fins 46 are provided over the entire circumference of the cylindrical portion 38B to form an annular shape.

  In the high temperature side housing 32, a liquid alkali metal, which will be described later, filling the first chamber 36 </ b> A is in contact with the anode side surface 42 on one side and the inner peripheral surface of the high temperature side housing 32 on the other side. I also serve.

  As shown in FIG. 2, the inner peripheral surface of the cylindrical portion 38 </ b> B of the solid electrolyte 38 has the same diameter over the entire area in the axial direction and the inner diameter does not change, and a smooth (smooth) cylindrical surface (circumference) Surface). Here, a smooth surface or a smooth surface means a continuous surface including a curved surface, and means a surface having no steep irregularities such as ridges and valleys. Thereby, the mold (core) at the time of sintering molding of the solid electrolyte 38 can be removed. Note that the cylindrical portion 38B may have a tapered shape in which the inner diameter increases toward the lower end opening for die cutting.

  A cathode (cathode electrode) 48 having conductivity and air permeability is formed on the inner surface of the solid electrolyte 38, that is, the cathode side surface 44. The cathode 48 is a thin film electrode made of molybdenum or the like, and is formed in a porous shape (three-dimensional network structure) so that gas and liquid alkali metal can pass therethrough. The cathode 48 may be formed by a known lamination technique such as sputtering, and is provided so as to cover most of the inner surface of the solid electrolyte 38, preferably the entire region. The inner peripheral surface of the cylindrical portion 38B has the same diameter over the entire region in the axial direction and the inner diameter does not change, and is formed in a smooth cylindrical surface. Therefore, the cathode 48 having a thin film structure without defects is formed by a known lamination method. It can be reliably and easily formed.

  A porous lead member 50 is provided inside the cathode 48 so as to fill the inner space of the cathode 48. The porous lead member 50 is formed of a porous metal body (a three-dimensional network structure foam metal body) through which gas and liquid alkali metals can pass, and contacts the entire surface of the cathode 48 and is electrically connected to the cathode 48. Has been. A connection terminal 52 made of a conductive material such as metal is fixed to the lower end portion of the porous lead member 50 in a conductive relationship with the porous lead member 50. The connection terminal 52 protrudes downward from the lower end surface of the porous lead member 50 and enters the communication opening 22 </ b> A formed through the insulating plate 22.

  As shown in FIG. 2, the low temperature side housing 54 of each cell 30 is provided below the disk member 16 in a suspended state. The low-temperature side housing 54 is made of a conductive material such as a metal having high thermal conductivity and high electrical conductivity, and has a cylindrical shape with a fan-shaped cross section whose upper end is closed by the upper end wall 54A and lower end is closed by the lower end wall 54B. And defines an internal hermetic cryogenic chamber 56. The low temperature side housing 54 is disposed in each opening 18, and the upper end wall 54 </ b> A is fixed to the lower part of each cell mounting substrate 20 in a conductive relationship. A plurality of fins 60 projecting radially outward from the outer peripheral surface are integrally formed in the cylindrical portion 54 </ b> C of the low temperature side housing 54 in order to increase the heat exchangeable surface area.

  The low temperature side housing 54 exists for each cell 30 and is fixed to each cell mounting substrate 20, so that, similarly to the high temperature side housing 32, the low temperature side housing 54 is rotationally symmetrical with respect to each other about the rotation axis X. Further, they are arranged at equal intervals around the rotation axis X with a rotation angle of 60 degrees. In the present embodiment, the high temperature side housing 32 and the low temperature side housing 54 are disposed at the same phase rotation position around the rotation axis X. The low temperature side housing 54 of each cell 30 is electrically insulated from each other by the electrically insulating disk member 16 that supports the cell mounting substrate 20, thereby ensuring individual electrical insulation without short-circuiting.

  As described above, the high temperature side housing 32 and the low temperature side housing 54 are individually configured, and are electrically connected to each other by the cell mounting substrate 20 and a pipe member 64 described later while maintaining individual electrical insulation for each cell 30. Has been.

  Each cell 30 is arranged at a rotationally symmetric position around the rotation axis X and at equal intervals around the rotation axis X by arranging the high temperature side housing 32 and the low temperature side housing 54 on each cell mounting substrate 20. Will be. Moreover, all the high temperature side housings 32 of each cell 30 are fixed to the upper side of the disk member 16, that is, the upper side along the rotation axis X, and all the low temperature side housings 54 of each cell 30 are below the disk member 16, that is, It is fixed to the lower side along the rotation axis X. Further, the high temperature side housing 32 of each cell 30 exists radially outward from the low temperature side housing 54.

  As shown in FIGS. 2 and 4, a fan-shaped extending plate-like portion 54 </ b> D extending radially outward from the upper end wall 54 </ b> D is integrated with the low temperature side housing 54 at the upper end portion of the low temperature side housing 54. Is formed. A projecting portion 20A having a frame shape having the same shape as the fan shape in which the upper end wall 54A and the extended plate-like portion 54D are continuous is formed on the lower bottom portion of the cell mounting substrate 20. The peripheral edges of the upper end wall 54A and the extended plate-like portion 54D are hermetically engaged with the entire circumference of the projecting portion 20A, whereby a passage 58 is defined between the cell mounting substrate 20 and the low temperature side housing 54. .

  The passage 58 extends in the radial direction of the rotary shaft 12 and passes through the communication opening 20B formed through the cell mounting substrate 20 in the radially outer portion and the communication opening 22A of the insulating plate 22 in the second chamber 36B. It communicates with the lower part. The passage 58 communicates with a radially inner (innermost) upper portion of the low temperature chamber 56 through a communication opening 54E formed through the upper end wall 54A in the radially inner portion. In this way, the second passage (return passage) that communicates the lower end of the second chamber 36B and the radially inner upper portion of the low temperature chamber 56 by the communication openings 22A and 20B, the passage 58, and the communication opening 54E. ) 62 is individually configured for each cell 30.

  A pipe member 64 made of a conductive material such as a metal is attached to the insulating plate 22, the cell attachment board 20, and the upper end wall 54A so as to penetrate therethrough. The pipe member 64 has a first passage (outward passage) 66 that communicates the radially outer (outermost) upper portion of the low temperature chamber 56 and the radially outer (outermost) lower end of the first chamber 36A. Each cell 30 is individually defined. At the same time, the pipe member 64 is in contact with the high temperature side housing 32 and conductively connects the high temperature side housing 32 to the cell mounting board 20 and the low temperature side housing 54.

  The first chamber 36A and the second chamber 36B, the first passage 66, the second passage 62, and the low temperature chamber 56 in the high temperature side housing 32 are in a vacuum, and these are filled with alkali metal. . In this embodiment, sodium which can pass through the solid electrolyte 38 which is β alumina or β ″ alumina by ionization is used as an alkali metal.

  The lower end portion of the rotary shaft 12 is connected to an output shaft (rotor shaft) 72 of a fixedly arranged electric motor 70 which is a rotational drive means by an electrically insulating coupling 68 with a torque transmission relationship. The high temperature side housing 32 and the low temperature side housing 54 of each cell 30 are rotationally driven around the rotation axis X together with the disk members 16 and 26 by the rotational output of the electric motor 70.

  Since the high temperature side housing 32 and the low temperature side housing 54 of each cell 30 are arranged at rotationally symmetric positions around the rotation axis X, the high temperature side housing 32 and the low temperature side housing 54 of each cell 30 are connected to the rotation axis X. Even if it rotates around, there will be no imbalance in rotational balance due to the eccentric load.

  Next, the wiring structure of the AMTEC 10 will be described. Here, for convenience of description of the wiring structure of the cells 30, the six cells 30 are individually described with identification codes # 1 to # 6 as shown in FIGS. There is.

  As shown in FIG. 2, an anode-side slip ring 76 that is electrically insulated from the rotary shaft 12 and the rotary shaft 12 are directly connected to the outer periphery of the rotary shaft 12 by an electrically insulating sleeve 74. The cathode side slip ring 78 which is in a relationship is attached to be spaced apart in the axial direction. A current collecting brush (not shown) connected to an external load is in sliding contact with the anode side slip ring 76 and the cathode side slip ring 78. Power is supplied to the external load from the AMTEC 10 that rotates around the rotation axis X by the slip rings 76 and 78 and the current collecting brush.

  The low temperature side housing 54 of the # 1 cell 30 forms one terminal which will be described later, and one end of a conductive connecting plate 80 is electrically conductive at the bottom of the low temperature side housing 54 as shown in FIGS. It is attached in a state. The other end of the conductive connection plate 80 is conductively connected to the anode side slip ring 76. Since the low temperature side housing 54 is electrically conductive with the high temperature side housing 32 by the tube member 64 and the cell mounting substrate 20, the anode (high temperature side housing 32) of the cell # 1 is electrically insulated from the rotary shaft 12 and is on the anode side. The conductive connection is established with the slip ring 76.

  As shown in FIG. 3, one end of a lead wire 82 is conductively connected to the connection terminal 52 of the cell 30 of # 1. The lead wire 82 extends outward through the upper and lower portions of the two insulating plates 22 and is conductively connected to the cell mounting substrate 20 of the adjacent # 2 cell 30. Similarly, one end of a lead wire 84 is conductively connected to the connection terminal 52 of the cell 30 of # 2. The lead wire 84 extends outwardly between the upper and lower sides of the two insulating plates 22 and is conductively connected to the cell mounting board 20 of the adjacent # 3 cell 30. One end of a lead wire 86 is conductively connected to the connection terminal 52 of the cell 30 of # 3. The lead wire 86 extends outwardly between the upper and lower sides of the two insulating plates 22 and is conductively connected to the cell mounting substrate 20 of the adjacent # 4 cell 30. One end of a lead wire 88 is conductively connected to the connection terminal 52 of the cell 30 of # 4. The lead wire 88 extends outwardly between the upper and lower sides of the two insulating plates 22 and is conductively connected to the cell mounting board 20 of the adjacent # 5 cell 30. One end of a lead wire 90 is conductively connected to the connection terminal 52 of the cell 30 of # 5. The lead wire 90 extends outwardly between the upper and lower sides of the two insulating plates 22 and is conductively connected to the cell mounting substrate 20 of the adjacent # 6 cell 30. Note that the lead wires 82, 84, 86, 88, and 90 do not contact the cell mounting substrate 20 of the cell 30 that is the extension source.

  Since the cell mounting substrate 20 is electrically conductive with the high temperature side housing 32 for each cell 30 through the pipe member 64 and the low temperature side housing 54, and further through the liquid alkali metal present in the pipe member 64, the lead wire 82, 84, 86, 88, 90 establish a serial connection circuit in which six cells 30 of # 1 to # 6 are connected in series.

  The connection terminal 52 of the # 30 cell 30 constitutes the other terminal of the above-described series connection circuit, and one end of a lead wire 92 is conductively connected to the connection terminal 52 of the # 6 cell 30. The other end of the lead wire 92 is conductively connected to a conductive connection plate 94 attached to the rotary shaft 12 in a conductive relationship. As a result, the cathode 48 of the cell 30 of # 6 is conductively connected to the cathode side slip ring 78 using the rotating shaft 12 as a conductor. Thus, the rotating shaft 12 forms a part of the conductive path, so that the conductive connection structure between the series connection circuit and the sword side slip ring 78 is simplified.

  The operation of the AMTEC 10 according to this embodiment will be described below.

  The AMTEC 10 rotates about the rotation axis X when the rotation shaft 12 is rotationally driven by the electric motor 70. As a result, the six cells 30 rotate together around the rotation axis X.

  Since the low temperature side housings 54 of all the cells 10 are in a low temperature environment, liquid alkali metal exists in the low temperature chamber 56, and this liquid alkali metal is caused by centrifugal force generated by rotation around the rotation axis X. Thus, it moves outward in the radial direction of the rotation axis X against gravity and moves upward along the radially outer wall surface of the low temperature chamber 56. Thereby, the liquid level L of the alkali metal (liquid) in the low temperature chamber 56 is as shown by a two-dot chain line in FIG. The liquid level L changes according to the rotational speed of the AMTEC 10.

  The liquid alkali metal moving upward in the low greenhouse 56 is transported to the first chamber 36A of the high temperature side housing 32 through the first passage 66 under the action of centrifugal force. As a result, the first chamber 36A is filled with the liquid alkali metal.

  Since the high temperature side housings 32 of all the cells 30 are in a high temperature environment, the temperature of the liquid alkali metal is raised in the first chamber 36A, and part of the alkali metal is evaporated to become a gas. The liquid and gaseous alkali metal emits electrons on the surface of the solid electrolyte 38 facing the first chamber 36 </ b> A, and enters the solid electrolyte 38 as alkali metal ions. The emitted electrons flow to the high temperature side housing 5 using the liquid alkali metal in the first chamber 36A as a conductor. Thereby, the high temperature side housing 32 of each cell 30 functions as an anode of each cell 30.

  Alkali metal ions in the solid electrolyte 38 receive electrons from the cathode 48 on the surface of the solid electrolyte 38 facing the second chamber 36B, and become gaseous alkali metal. The gaseous alkali metal passes through the porous lead member 50 of the second chamber 36 </ b> B and returns to the low temperature chamber 56 through the second passage 62. The alkali metal returned to the low greenhouse 56 is liquefied and transported to the first chamber 36A of the high temperature side housing 32 through the first passage 66 again under the action of centrifugal force.

  In this manner, the alkali metal circulates through the high-temperature side housing 32 and the low-temperature side housing 54 including the solid electrolyte 38 in an independent flow for each cell 30.

  The process in which the alkali metal becomes alkali metal ions and enters the solid electrolyte 38 from the first chamber 36A and the process in which the alkali metal ions become gaseous alkali metal and moves from the solid electrolyte 38 to the second chamber 36B A potential difference is generated between the (high temperature side housing 5) and the cathode 48.

  In the present embodiment, the fin 46 increases the surface area of the anode side surface 42 of the solid electrolyte 38 relative to the surface area of the cathode side surface 44, and the first chamber 36 </ b> A of the anode side surface 42 of the solid electrolyte 38 is increased in accordance with this surface area increase. The area in contact with the alkali metal increases.

  Thereby, the probability that an alkali metal having high kinetic energy is located in the vicinity of the anode side surface 42 of the solid electrolyte 38 is increased, and the number of ions entering the solid electrolyte 38 is increased. Accordingly, the amount of electrons separated on the anode side of the solid electrolyte 38 is increased, and the power generation efficiency of each cell 30 is improved.

  Since the anode (high temperature side housing 32) and the cathode 48 of the six cells 30 are connected in series between the anode side slip ring 76 and the cathode side slip ring 78, the anode side slip ring 76 and the cathode 48 are connected. Between the side slip ring 78, a potential difference of a total value of potential differences generated between the anode (the high temperature side housing 32) of each cell 30 and the cathode 48 is generated.

  In order to obtain a high voltage, when a plurality of cells 30 are electrically connected in series, in order to avoid an electrical short circuit between the cells 30 due to the liquid alkali metal, the alkali metal is used to connect the solid electrolyte 38. The high temperature side housing 32 and the low temperature side housing 54 that are included need to be circulated and transported in an independent flow for each cell 30. In contrast, the transport of the alkali metal in each cell 30 is performed by the centrifugal force generated when all the cells 30 are rotated around the rotation axis X by the rotation drive of the rotation shaft 12 by the electric motor 70. It is not necessary to provide a transportation means for transporting the alkali metal every 30th. Thereby, the AMTEC 10 in which a plurality of cells 30 are electrically connected in series can be configured compactly while avoiding duplication of transportation means.

  Since the high temperature side housing 32 of each cell 30 is collected on one end side in the axial direction (rotation axis X) of the rotation shaft 12 and the low temperature side housing 54 is collected on the other end side, the rotation around the rotation axis X is concerned. Instead, the plurality of high temperature side housings 32 can always be exposed to a common high temperature heat source, and the plurality of low temperature side housings 54 can always be exposed to a common low temperature side heat source. Thereby, the operation | movement with the temperature management of AMTEC10 becomes easy. Further, the high temperature side housing 32 of each cell 30 is collected on one side (upper side) of the disk member 16 which is a common support for the high temperature side housing 32 and the low temperature side housing 54 which are individually configured, and the other side. Since the low temperature side housings 54 of the respective cells 30 are gathered on the (lower side), the structure is simplified, and at the same time, the high temperature side and the low temperature side are clearly partitioned by the disk member 16, and this also causes the AMTEC 10 Temperature management becomes easier.

  Further, since the high temperature side housing 32 is made of a conductive material, the high temperature side housing 32 also serves as an anode, and it is not necessary to separately configure an anode on the anode side surface 42 of the solid electrolyte 38. Accordingly, the fins 46 can be provided on the anode side surface 42 of the solid electrolyte 38 without being restricted by configuring the anode. The disk member 16 that supports the high-temperature side housing 32 of each cell 30 is made of an electrically insulating material, so that even if the high-temperature side housing 32 is made of a conductive material, an electrical short circuit is generated between the cells 30. The plurality of cells 30 can be electrically connected in series without occurring.

  FIG. 5 shows a usage example of the AMTEC 10 using the exhaust gas of the internal combustion engine, which is waste heat, as a heat source. In other words, the high temperature side housing 32 that is a heat receiving part of the AMTEC 10 is disposed above the disk member 16 in the main passage 102 of the exhaust pipe 100 of the internal combustion engine so as to be able to exchange heat with the exhaust gas flowing through the main passage 102. Yes. As a result, the high temperature side housing 32 is heated by the exhaust gas. The heating temperature of the high temperature side housing 32 by the exhaust gas may be 500 ° C. or higher.

  In other words, the low temperature side housing 54, which is a heat radiating part of the AMTEC 10, is disposed in the bypass passage 104 parallel to the main passage 102 on the lower side of the disk member 16. The exhaust gas inlet 106 of the bypass passage 104 is configured to be opened and closed by an on-off valve 108. An outside air inlet 110 is formed in the bypass passage 104, and a reed valve 112 for taking in outside air is attached to the outside air inlet 110. Reference numerals 114 and 115 denote hermetic rotary seal portions.

  When the AMTEC 10 is started, in order to preheat the heat radiating portion (low-temperature side housing 54), the on-off valve 108 is opened, exhaust gas flows through the bypass passage 104, and the heat radiating portion is heated by the exhaust gas. The preheating of the heat radiating portion is performed to liquefy the alkali metal that has become solid in the low temperature chamber 56. After the preheating of the heat dissipating part is completed, the on-off valve 108 is closed, the outside air is taken into the bypass passage 104 by the reed valve 112, and the heat dissipating part is kept at a lower temperature than the heat receiving part. The appropriate temperature of the heat radiating portion is determined by the temperature of the heat receiving portion, and may be about 100 to 500 ° C.

  Thereby, the AMTEC 10 operates using the exhaust gas of the internal combustion engine as a heat source.

  Although the description of the specific embodiment is finished as described above, the present invention is not limited to the above embodiment and can be widely modified. For example, the number of cells 30 can be appropriately increased or decreased according to the purpose of use and the required voltage. The series connection structure of the cells 30 is not limited to that of the above-described embodiment, and can be implemented in various modes such as one using a wiring board having heat resistance.

  In the above-described embodiment, the anode side slip ring 76 is attached to the rotary shaft 12 in an electrically insulated state, and the cathode side slip ring 78 is attached to the rotary shaft 12 in an electrically conductive state. The slip ring 76 may be attached to the rotating shaft 12 in an electrically conductive state, and the cathode side slip ring 78 may be attached to the rotating shaft 12 in an electrically insulated state. In this case, the connection of the series connection circuit to both slip rings is also reversed.

  Further, the unevenness for increasing the contact area with the alkali metal on the anode side of the solid electrolyte 38 is not limited to the fin 46, and may be a bellows shape, a projection or a depression such as a hemisphere. Also good.

  In addition, all the components shown in the above embodiment are not necessarily essential, and can be appropriately selected without departing from the gist of the present invention. The fins 46 and the like of the solid electrolyte 38 are not essential and may be omitted.

10 Alkali metal thermoelectric converter (AMTEC)
12 Rotating shaft 16 Disk member (plate member)
20 Cell mounting substrate 22 Insulating plate 27 Solid electrolyte 30 Cell 32 High temperature side housing 36 High greenhouse 36A First chamber 36B Second chamber 38 Solid electrolyte 46 Fin 48 Cathode 50 Porous lead member 52 Connection terminal 54 Low temperature side housing 56 Low greenhouse 62 Second passage 66 First passage 70 Electric motor 76 Anode side slip ring 78 Cathode side slip ring 80 Conductive connection plate 82 Lead wire 84 Lead wire 86 Lead wire 88 Lead wire 90 Lead wire 92 Lead wire 94 Conductive connection plate

Claims (7)

A high temperature side housing that receives heat and a high temperature side, a low temperature side housing that dissipates heat and a low temperature, and a high temperature chamber in the high temperature side housing are divided into a first chamber and a second chamber. A solid electrolyte that allows the passage of ions, an anode provided in the first chamber, a cathode provided in the second chamber, a low temperature chamber in the low temperature side housing, and a first chamber communicating with the first chamber. A plurality of cells having one passage, a second passage communicating the low temperature chamber and the second chamber, and a liquid alkali metal stored in the low temperature chamber;
The cells are arranged around one axis of rotation;
The high temperature side housing is disposed on one side along the rotation axis;
The low temperature housing is disposed on the other side along the rotation axis;
Furthermore, a series connection circuit that electrically connects the plurality of cells in series;
A drive device for rotating all of the cells around the rotation axis;
An alkali metal thermoelectric converter that moves the alkali metal in the low-temperature chamber to the first chamber through the first passage by a centrifugal force generated by rotation about the rotation axis. A plate-like member extending in a direction perpendicular to the rotation axis;
In the cell, the high temperature side housing and the low temperature side housing are individually configured, all of the high temperature side housings are fixed to one side of the plate member, and all of the low temperature side housings are the plate member. The alkali metal thermoelectric converter according to claim 1, which is fixed to the other side.   3. The alkali metal thermoelectric converter according to claim 2, wherein the high temperature side housing is made of a conductive material and serves also as the anode, and the plate-like member is made of a material having electrical insulation. A rotation shaft disposed concentrically with the rotation axis and having the plate member attached thereto;
One of the anode side and cathode side slip rings is attached to the rotating shaft in an electrically insulated state, the other is attached in an electrically conductive state, and one terminal of the series connection circuit is the one of the ones 4. The alkali metal thermoelectric converter according to claim 2, wherein the slip ring is conductively connected to the rotary shaft in an electrically insulated state, and the other terminal of the series connection circuit is conductively connected to the rotary shaft.   Each of the high temperature side housings is disposed at a position that is rotationally symmetric with respect to the rotational axis, and each of the low temperature side housings is disposed at a position that is rotationally symmetric with respect to the rotational axis. The alkali metal thermoelectric converter according to any one of 1 to 4.   The alkali metal thermoelectric converter according to any one of claims 1 to 5, wherein a portion of the solid electrolyte facing the first chamber is provided with irregularities for expanding the surface area of the solid electrolyte.   The alkali metal thermoelectric converter according to any one of claims 1 to 6, wherein the high temperature side housing is arranged to be able to exchange heat with exhaust gas of an internal combustion engine.

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